User's Manual

UNIVAC SDF TAPE FORMAT
11-10 XEROX LASER PRINTING SYSTEMS TAPE FORMATS MANUAL
Data records
Data records (format is shown in figure 11-3) are identified by the first
field of the record having a positive value. The first 36 bits of the data
record contain the length of the print data, a line spacing value
indicating the number of lines to be spaced before printing, and a
code type indicating whether the print data is Fieldata or ASCII.
Figure 11-3. Univac SDF data record format
Length Data records are of variable length. At the end of a block that is a
fixed length, a data record probably spans to the next block. The data
record is split into two parts and the second block starts with a
continuation data record (type O'51'). The two parts of the data
record are rejoined and printed as one.
In release levels prior to Level 37 for Univac software, blocks were
always 224 Univac words in length. The continuation data record
(type O‘51’) generally appeared at the beginning of each block. In
release level 37 and above, block sizes have been increased to
multiples of 224 words, up to 1792 words. The O‘51’ record can then
occur on any 224 word boundary within the data block.
Overprint/merge processing On print lines for which carriage control requires overprinting,
overprint/merge processing is handled according to the JDE option
selected.
Spacing Data record spacing of “m” lines is processed as follows:
• In general, the new current line number is set to the old
calculated line number + m.
• If the new current line number is then greater than bottom-of-
form, a page overflow occurs and the new current line number
is set to top-of-form - 1 (to allow the next line to be printed top-
of-form).